Shear fracture energy of asphalt-aggregate systems and its application to predicting shear fatigue in asphalt mixtures

This study focuses on stress–displacement curves and shear fracture energy of asphalt-aggregate systems subjected to direct shear loading for four different experimental conditions. The methodology for measuring shear fracture energy of asphalt-aggregate specimens is presented. Based on comparison of the experimental data, this paper indicates that the single-peak curves (SPCs) tend to envelop the double-peak curves (DPCs) and the values of shear fracture energy of the SPCs are much higher than those of the DPCs for each experimental condition. Using thermodynamic theory and slip theory, energy of interaction between the adhesion and the cohesion within the asphalt-aggregate systems is further analysed. The experimental results clearly show that the reduced fracture energy of the DPCs is related to the shear-dependent slip, including adhesive slip and cohesive slip that occur simultaneously and promote each other in the direct shear testing. This study also illustrates that fracture energy is capable of being a significant parameter in the failure and healing analysis of asphalt pavements.